Universal serial bus (“USB”) sticks consist of a memory data storage device integrated with a USB interface. USB sticks are typically used for similar purposes for which floppy disks or CD-ROMs were previously used. However, USB sticks are smaller, faster, have thousands of times more capacity, and are more durable and reliable. In the case of USB sticks with chip on board (“COB”) flash memory, a USB controller and flash memory can be combined into one structure that is embedded into one side of a printed circuit board (“PCB”) with the USB connection located on an opposing surface.
The USB standard that governs the design of the USB connections has undergone several revisions since its earliest release in 1994. The first widely adopted version, USB 1.1, specified data rates of 1.5 Mbit/s (“Low-Bandwidth”) and 12 Mbit/s (“Full-Bandwidth”). USB 1.1 was replaced by USB 2.0 in 2000. USB 2.0 provided a higher maximum data rate of 480 Mbit/s (“Hi-Speed”). In this version, the USB 2.0 cable has four wires: two wires for power (+5 volts and ground) and a twisted pair of wires for carrying data. In the USB 2.0 design, as well as USB 1.1, data is transmitted in one direction at a time (downstream or upstream).
In 2008, a new USB 3.0 standard was announced. USB 3.0 includes a new “SuperSpeed” bus, which provides a fourth data transfer mode at 5.0 Gbit/s. In order to achieve this increased throughput, the USB 3.0 cable has a total of eight wires: two wires for power (+5 volts and ground), the twisted pair for carrying non-SuperSpeed data (allows backward compatibility with earlier versions of USB devices), and two differential pairs for carrying SuperSpeed data. Full-duplex signaling occurs over the two differential pairs.
To date, adoption of the USB 3.0 standard has been slow due to the need to re-design motherboard hardware that supports the USB 3.0 standard, and the need to revise operating systems to support the USB 3.0 standard. To ease the transition to the USB 3.0 standard, it is desirable to modify existing USB 2.0 COB sticks to also include USB 3.0 connections.
Because the USB 2.0 COB stick configuration has a rectilinear design with the components embedded on one side of the PCB and the USB 2.0 connections positioned flush with the opposing side of the PCB, the shape and configuration does not readily allow the addition of a USB 3.0 connection to the existing USB 2.0 COB stick. With USB 3.0 being the coming standard and much faster than USB 2.0, it is desirable to provide a design that incorporates USB 3.0 connections into existing USB 2.0 COB sticks so that the USB COB stick may connect to either version of the USB standard.